Vacuum pumping unit



J ly 1 1963 G. E. v. MONGODlN 3,392,538

VACUUM PUMPING UNIT Filed 001:. 26, 1966 2 Sheets-Sheet 1 .5 J F Z 7 2/6 l. g, m 1 I a 6 APPLICANT GUY EMILE Vic-rug Mensch/N Ammvzvs July 16, 1968 G, E. v. MONGODIN VACUUM PUMPING UNIT 2 Sheets-Sheet 2 Filed Oct. 26, 1966 APPLICANT Gov Emma. V/cm MaNGaoW 51,14 him United States Patent 3,392,538 VACUUM PUMPING UNIT Guy Emile Victor Mongodin, Fresnes, France, assignor to Societe Anonyme: Societe Alsacienne de Constructions Atomiques de Telecommunications et dElectronique Alcatel, Paris, France, a corporation of France Filed Oct. 26, 1966, Ser. No. 589,695 Claims priority, application France, Oct. 27, 1965,

3 Claims. bl. 6255.5)

ABSTRACT OF THE DISCLOSURE A casing for housing a suction pump circuit including a diffusion pump, at least one trap and at least one valve wherein the casing comprises a solid unitary block having cavities formed therein for accommodating and housing the components of the pump circuit therewithin.

The present invention relates to a unitary compact block for housing the various elements of a suction pump circuit. In suction techniques, the traditional design of diffusion pumps,traps, and valves in the form of separate devices with a suction flange and a delivery flange, make it difficult to form a compact assembly of the diffusion pump with the baffles, traps, valves, and other devices necessary to make a complete suction circuit.

The object of this invention is to provide complete suction circuits comprising at least one diffusion pump, at least one trap, and at least one valve, all these parts being assembled in an extremely compact and economical manner.

According to the present invention, a unitary compact block for housing the various elements of a suction pump circuit namely the previously mentioned parts comprises a casing in which cavities for the diffusion pump body and for the body (or bodies) of the trap and valve are machined, the various said cavities being connected by apertures formed in the block and serving as pipes connecting together the different members of the suction circuit. Such a block may be likewise utilised for detecting leaks.

It will immediately be understood that the pumping block thus constituted eliminates numerous joints and connecting flanges which are required in conventional suction pumping circuits and which are sources of gas losses and lealcs.

In addition, if the casing is constructed in a forged or cast block, complete tightness is immediately ensured because there are no welded joints. An assembly of this type likewise permits mechanical construction of precision and great strength.

A construction of this type considerably simplifies the problem of cooling the pump, which is achieved in two manners:

(1) The surface effecting cooling, at least in the case of an air cooled pump, may be considerably enlarged, by the use of fins distributed over the greater part of the block.

(2) The great calorific inertia of the assembly permits the stopping of the cooling source of the pump, working 'by air or by water, as soon as the heating of the pump is stopped, so that there is a saving in working time.

One form of construction of a suction pumping unit constructed in accordance with the invention is described hereinbelow, simply by way of example and without limitation, with reference to the accompanying drawings, in which:

FIGURE 1 shows the theoretical diagram of the pumping circuit to be produced;

FIGURE 2 illustrates diagrammatically the manner in Patented July 16, 1968 FIGURE 3 illustrates diagrammatically an alternative I arrangement in which the pre-exhausting pump is separate from the primary pump;

FIGURE 4 illustrates the manner in which the cavities of the different elements are formed in the block.

In the embodiment illustrated in FIGURE 1, the pumping circuit to be provided comprises a diffusion pump 1, preexhausted by a primary pump 2, a suction valve 3 situated between the suction side of the diffusion pump 1 and a liquid nitrogen trap 4, a suction valve 5 situated between said trap and a suction flange 6, while, on the pipe connecting the valve 5 and the flange 6, there are branched in parallel an air re-entry valve 7 and a by-pass valve 8 enabling the primary pump 2 to be used as a preexhausting pump.

This suction circuit constitutes a very conventional assembly in suction technique and has the disadvantages referred to hereinabove.

According to the invention a circuit of this type is constructed as illustrated in FIGURE 2.

All the elements of the aforesaid suction circuit, with the exception of the primary pump, are integrated in a single block or casing 10 in which the housings for said elements are hollowed out or provided.

The situation of all the aforesaid elements can clearly be seen; thus the boiler 11 of the diffusion pump 1, a control 12 for the valve 3, a pocket 13 for the liquid nitrogen trap 4, a control 14 for the valve 5, the suction flange 6, a control 15 for the valve 7, a control 16 for the valve 8, and an air inlet 17 for the air re-entry valve 7.

It is seen that the number of connections is reduced to three; the suction flange 6, a junction 18 between the diffusion pump 1 and the primary pump (not illustrated), and finally a junction 19 between the bypass pipe and the primary pump, whereas in a conventional design each of the elements would be connected to the others by two pipes (one upstream pipe and one downstream pipe).

FIGURE 3 illustrates the same suction circuit as in FIGURE 1, but includes a pre-exhausting pump 9 which, by means of the by-pass valve 8, can be connected to or disconnected from the circuit. This arrangement is particularly suitable when the equipment has to 'be used for the detection of leaks.

FIGURE 4 shows how it is possible to construct a compact suction pumping unit in accordance with the above description.

For this purpose use is made of a preferably forged metal block 10 in which there are made passages and cavities of suitable diameters simply by drilling and boring operations.

A cylindrical cavity 20 is provided to receive the diffusion pump 1, a passage 21 constitutes the pipe for connection to the primary pump via the junction 18, and a bore 22 forms the seat for the valve 3 situated in a cavity 23.

A passage 25 constitutes the pipe for connecting the valve 3 annd the liquid nitrogen trap 4 situated in a cylindrical cavity 26. Said cavity is connected by a passage 27 to a lateral cavity 28 .for receiving the valve 5, and the peripheral edge 29 of the passage 27 forms the seat of said valve.

A bore 30 passing through the cavity 28 constitutes the passage connecting the valve 5 to the suction flange 6, and a passage 31, formed at the bottom of a cavity 32, is provided to receive the valve 7 and leads into said bore. The peripheral edge 33 of the passage 31 forms the seat of said valve.

A passage 34 formed radially in relation to a cavity 32 constitutes the passage leading to the air intake 17.

A passage 35 formed at the bottom of a cavity 36 is provided for receiving the valve 8 and also leads into the bore 30. The peripheral edge of the passage 35 forms a seat 37 for said valve.

A passage 38 formed radially in relation to the cavity 36 constitutes the connecting passage between the bypass valve 8 and the primary pump.

The block 10 is provided with fins 10' over all or part of its peripheral surface. These fins facilitate the cooling of the whole arrangement and particularly the cooling of the oil; now, it is known that the temperature to which the oil is cooled determines the limit value of the vacuum which can be obtained. The cooling may be further accelerated and/or increased by placing the block in front of a fan blowing along the larger faces of the block.

It is seen that by this machining of a single block of metal a complete vacuum circuit has been obtained which requires only the three abovementioned connections.

It will be observed that the aforesaid machining has the effect that all the cavities and certain of the holes lead to the outside of the block 10. Only one aperture, the aperture 39, is not used, but is necessary in order to permit the machining of the passage 25 and must be closed by a plug 40.

The construction of a vacuum circuit in the form of a compact block as described above is particularly suitable for utilizing an air cooled pump.

Although experience has shown that this is not indispensable, fins may be milled on the block 10 in order to increase the dissipation of heat therefrom as state-d above.

In the case of the utilization of a Water cooled pump, it is possible to drill passages in the block so as to constitute a cooling circuit in accordance with the invention. A refrigerating liquid may thus be passed through this cooling circuit, thereby increasing the effectiveness of the traps.

The advantages of the block according to the invention will be summarized below:

Tightness is more reliable through the reduction of the number of joints, thus resulting in low loss of gas;

The pump is cooled in the volume of the block instead of cooling being effected by the transmission of heat to a single surface. A large ventilatable surface is available, so that better cooling is effected; v

The block has great rigidity; vacuum installations are generally made of non-rusting metal, such as steel, because aluminium is fragile in the small dimensions used in coppersmiths work, whereas by making a machined block a rigid and compact part is obtained;

The dimensions given to the valves may be as large as desired;

The machining of the block eliminates considerable coppersmith and assembly work and thus permits considerable reduction of cost price;

When the block is used for detecting leaks, the advantage is gained of high resistance to shocks, thus enabling this equipment to be embarked in space vessels, while moreover the very accurate outer surfaces of the block enable useful accessories to be arranged and held therein, even in an overhung arrangement, for example a detector analysis cell.

What is claimed is:

1. A casing for housing the components of a suction pump circuit including a diffusion pump, at least one trap, and at least one valve comprising a solid unitary block having substantially fiat sides, cavities extending from said sides into said block and thence opening into other of said sides, passages interconnecting said cavities, said diffusion pump, traps and valves being arranged and contained in said cavities whereby said pump circuit is integrated within said solid block.

2. A block as claimed in claim 1 wherein said block is metal and said cavities are machined therein and including fins formed in at least one side of said block to assist cooling of the unitary block.

3. A block as claimed in claim 2 wherein said cool ing fins are machined in the block.

References Cited UNITED STATES PATENTS 3,119,243 1/1964 Hnilicka, et al. 6255.5 3,168,819 2/1965 Santeler 62-555 3,252,291 5/1966 Eder 6255.5 3,262,279 7/1966 Moore 62-55.5

LLOYD L. KING, Primary Examiner. 

